Terahertz band communication using plasma wave propagation in multilayer graphene heterostructures

Abstract

Graphene-based heterostructures provide a viable platform to implement optoelectronic devices that can operate in the terahertz (THz) band. In this study, the authors focus on multilayer (ML) graphene as the building block to implement high-frequency and low-energy plasmonic interconnects for on-chip signalling in next-generation systems. Two specific plasmonic interconnect geometries are analysed: single waveguide (SWG) and parallel-plate waveguide (PPWG). While SWG interconnects support propagating surface plasmons that are polarised in the transverse magnetic direction, in PPWG interconnects, nearly dispersion-less quasi-transverse electromagnetic modes are supported. The dispersion characteristics are derived by solving Maxwell's equations in the device setup in which ML graphene presents an impedance boundary condition. The effects of number of layers, electrostatic screening, and Fermi level are included in the model of intra-band dynamical surface conductivity of ML graphene. The authors also develop analytical models of energy-per-bit and bandwidth density for both SWG and PPWG interconnects. The energy dissipation includes the effect of plasmon generation, detection, and modulation circuitry within a thermal- and shot-noise-limited transmission of information. They quantify optimal interconnect length scales for which plasmonic interconnects provide lower energy and higher bandwidth when compared against their electrical (copper/low- κ ) counterparts at the 2020 ITRS technology node.